The purpose of this project is to study the kidney, the small blood vessels and the lung in various diseases by means of special light microscopy techniques, immunofluorescence microscopy, electron microscopy and by chemical and histochemical methods, and to correlate the structural and chemical variations with physiological parameters and with clinical behavior. Encompassed in the study will be intrinsic renal diseases such as glomerulonephritis, systemic diseases, particularly diseases of connective tissue which involve the kidney and the small blood vessels, various diseases of the lung affecting the alveolar septa and their capillaries and renal, pulmonary and vascular abnormalities induced by various means in experimental animals. Extensive use of biopsy material, primarily that of the kidney, but also of the lung and connective tissue will permit simultaneous evaluations of structure and function and will also allow to follow the development of the disease from its inception to resolution or to a fatal outcome. Study of biopsies will be supplemented by autopsy material wherever this will be available. It is hoped to develop a better understanding of the nature of diseases involving the kidney, the small blood vessels and the connective tissue and also to contribute to elucidation of normal morphology.